to braze or not to braze.....

[PawPaDawg]

Hello everyone,
I recently purchased a 12' aluminium jon boat that came with a min kota 35 troling motor, trailer, new oars and two swivel seats.
I know nothing about boats.
The guy showed me the trolling motor worked in all 4 speeds forward and reverse.
Said he filled it with water and saw no leaks.
Showed me where he "totaly rebuilt the transom"
Saw new 3/4" plywoid ( he said it was marine grade)
New tires and led lights on trailer.
Paint was faded but i could not see and cracks and i did not see any dents or "waves" in the side and bottom skins. $450.00
Was invited to lake for 4th of july.
Took boat to the lake, set boat in the water . IMMEDIATELY it was taking on water, not a bunch, just enough that i had concerns about kiddos fishing with me.
Loaded boat back onto trailer, returned to campsite and looked boat over....this is what i found and where i need advice for best repair. ..

Middle seat has 2 loose rivets,
Back seat has 3 missing rivets,
Transom repsier he did he did NOT seal the bolt holes he drilled and they had no rubber washers on either side, bolts were on HAND TIGHT!!!
upon further examibatiin i noticed where at the back of the boat there are 2 gossit looking pieces from the side to the transom that looked "bubbled".
a closer look revealed it to be epoxy or jb weld that was not properly done and was peeling. When i peeled it i noticed a crack slong the welds ON BOTH SIDES. Whrn i looked at the rivets on the inside that were leaking....more epoxy that peeled.

I have expierence in welding. Gas and stick.
I have a dnall 110v stick welder for small crafts i build for my wife.
Was wondering....need i try to braze with ixy/aceyt...or might i be able to purchase small aluminum welding rod to seal up these rivets and fix those cracks?
Was thinking of adding a foam I insulation type floor covered in rubber. ?????
How can i reinforce the sides?
Can i use rhino liner on the bottom to protect it when i beach her?
Lastly.....what size of outboard would be best?
5hp, 10hp,15hp,20hp?
Saw in you tube 12' jon with 40hp.....looked dangerous.
Any and all advice is greatly appreciated.
Want to take my scam boat and make her a great lil fishing boat.

 

[fishrdan]

Post up a picture of the cracked welds. I wouldn't try to braze it as the aluminum brazing rods are not easy to use. I've used them a couple of times, and they worked for the purpose, but I wouldn't use them for most repairs.

Buck the loose rivets and replace the missing rivets, don't try to weld them. Closed end blind rivets (pop rivets) may fit the bill, but you can also buy solid aluminum rivets online. Worst case - replace the missing/loose rivets with SS truss head machine screws, washers and nuts sealed up with 3M 5200. I wouldn't be surprised if you find more loose rivets... Check out an epoxy sealer called Gluvit, lots of guys here have used it to seal up the rivets of old tinny's. (I don't have any experience with Gluvit, but have heard it mentioned many times in the resto threads.)

The transom plywood needs to be sealed up or treated. Marine plywood (most) is not treated and will rot just like cheap doug fir plywood. The transom hardware should be sealed with 3M 5200. I use SS fender washers against the plywood so the fasteners don't punch through the wood.

 

[jbcurt00]

Bolts need to be sealed thru the holes in the transom, not w rubber washers. I prefer stainless bolts, washers on both sides and a nylock nut. You dont want to use galvanized or zinc coated steel, they react w the aluminum.


IMO, its a riveted boat, and should have riveted repairs, not welded. The existing welded repairs have already cracked.

Closed end blind rivets w aluminum mandrels. Fastenall or RivetsOnline are popular places as is McMaster Carr.

Remove and replace loose rivets. You can try to re-buck them, but I'd replace them.

See if your local recycler will sell you some pieces of sheet aluminum to patch over the areas w cracks after stop drilling the ends of the cracks. Specifics @ repair pending pix of the actual cracks.

Why reinforce the sides? To remove the benches?

Bedliner directly on the boat hull isnt what I'd choose to do. IMO, hard to get a good bond everywhere to the aluminum, and a real bear to remove what is well stuck when it starts to peel.

7.5hp to 12hp is typically a 12ftrs recommended OB size.

Whats the beam (width) of yours? My current 12ftr is nearly 5ft wide, and rated for a 12hp, my previous 12ftr was narrower, IIRC, 42in, and rated for a 7.5hp.


Pix help
http://forums.iboats.com/forum/forum-rules-and-guidelines/9938375-photo-upload-tutorial

 

[fhhuber]

There's a special "solder" for aluminum called "Dura Fix" Or you Tig weld it. Don't try to braze it.

Any crack has to be stop-drilled regardless of the type fix. You drill a hole at the end(s) of the crack at least 1/16 inch dia (and better be sure you actually got the end...) or the crack will continue to spread.

Loose rivets can usually be "rebucked". You put a heavy block of metal on one side and flatten it down more with a hammer (better if you use the proper punch also)

You will probably never 100% stop all leaks on a riveted old aluminum hull. I had mine down to appx 1 cup of leaking per 4 hours. I got more over the back of the transom launching the boat... so that was good enough.

Rubber washers on transom bolts are not common.

12 ft jon boat appx 10 -15 hp if you don't have a label. The label might say up to 35 if it has one... but there are a lot of different 12 ft jon boats out there and some have stronger transoms than others.

See this post RE treating wood to make it last longer
http://forums.iboats.com/forum/boat-...ist-resoration

 

[jbcurt00]

Marine plywood needs to be SEALED as does any exterior grade plywood used in a boat, not treated. Dont use pressure treated plywood anywhere on an aluminum boat.